In recent years, the inkjet recording method provides a handy and cost-effective way of producing an image, and has been extensively employed over an extensive range including photographing, various forms of printing, marking, special printing on color filters. In particular, this technique provides image quality comparable to that of silver halide photography, using a recording apparatus for jetting minute dots and controlling them; an ink characterized by improved color reproduction range, durability and jetting suitability; and special-purpose paper accompanied by a drastic enhancement in ink absorption, good color development, coloring material and surface gloss. The current enhancement of image quality by the inkjet recording method is achieved only when all of the three factors—recording apparatus, and ink and special-purpose paper—have been upgraded.
However, an inkjet system requiring use of special-purpose paper encounters such problems as restrictions on the recording medium and overruns of the recording medium cost. To solve these problems, numerous attempts have been made to use the inkjet method to record on a transfer medium different from special-purpose paper. To put it more specifically, such techniques include the phase-change inkjet method for using a solid wax ink at room temperature, the solvent-based inkjet method using an ink mainly composed of quick-drying organic solvent, and the UV inkjet method that uses ultraviolet rays (UV) for cross linking.
Of these techniques, the UV inkjet method is less foul smelling and dries more quickly than the solvent based inkjet method, and permits recording on paper that does not absorb ink. For these reasons, the UV inkjet method is drawing attention, and ultraviolet cure ink for inkjets have been disclosed (e.g., Patent Documents 1 and 2).
However, even when such ink is used, stable emission of ink may not be achieved, depending on the type of the recording medium and working environment. Further, there is a great change in the diameter of the dots having been emitted, and a high-definition image cannot be formed on various recording media, according to the prior art.
In particular, the ink for ultraviolet cure inkjet using cation polymerized compounds is not subjected to oxygen inhibition, but is vulnerable to the adverse effect of the water content (moisture) on the molecular level (e.g., Patent Documents 3 through 5).
The activated light curable inkjet ink containing the modified silicone oil has been known in the prior art (e.g., Patent Document 6). The modified silicone oil used in such a technique causes drastic reduction in the surface tension of ink. Thus, the prior art has failed to ensure both stable ink emission and high-definition image formation in various printing environments.
[Patent Document 1] Official Gazette of Japanese Patent Tokuhyo 6-200204 (Claim and Embodiment)
[Patent Document 2] Official Gazette of Japanese Patent Tokkai 2000-504778 (Claim and Embodiment)
[Patent Document 3] Official Gazette of Japanese Patent Tokkai 2001-220526 (Claim and Embodiment)
[Patent Document 4] Official Gazette of Japanese Patent Tokkai 2002-188025 (Claim and Embodiment)
[Patent Document 5] Official Gazette of Japanese Patent Tokkai 2002-317139 (Claim and Embodiment)
[Patent Document 6] Official Gazette of Japanese Patent Tokkai 2003-147233 (Claim and Embodiment)
The present invention is intended to solve the aforementioned problems. It is accordingly an object of this invention to provide an activated light curable inkjet ink capable of ensuring stable ink emission, excellent character quality without color mixture, and stable recording of high-definition images in various printing environments, and to provide as an image formation method and inkjet recording apparatus using this activated light curable inkjet ink.